Oversight control of an adaptive noise canceler in a personal audio device
First Claim
1. A personal audio device, comprising:
- a personal audio device housing;
a transducer mounted on the housing for reproducing an audio signal including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer;
a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds;
an error microphone mounted on the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer; and
a processing circuit that implements at least one adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit implements a coefficient control block that shapes the response of the at least one adaptive filter in conformity with the error microphone signal and the reference microphone signal by computing coefficients that determine the response of the adaptive filter to minimize the ambient audio sounds at the error microphone, and wherein the processing circuit detects that an ambient audio event is occurring that could cause the adaptive filter to generate an undesirable component in the anti-noise signal and changes the adapting of the at least one adaptive filter independent of the computing of the coefficients by the coefficient control block, wherein the ambient audio event is wind noise, scratching on the housing of the personal audio device, a substantially tonal ambient sound, or a signal level of the reference microphone signal falling outside of a predetermined range.
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Accused Products
Abstract
A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is also provided proximate the speaker to measure the ambient sounds and transducer output near the transducer, thus providing an indication of the effectiveness of the noise canceling. A processing circuit uses the reference and/or error microphone, optionally along with a microphone provided for capturing near-end speech, to determine whether the ANC circuit is incorrectly adapting or may incorrectly adapt to the instant acoustic environment and/or whether the anti-noise signal may be incorrect and/or disruptive and then take action in the processing circuit to prevent or remedy such conditions.
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Citations
21 Claims
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1. A personal audio device, comprising:
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a personal audio device housing; a transducer mounted on the housing for reproducing an audio signal including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds; an error microphone mounted on the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements at least one adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit implements a coefficient control block that shapes the response of the at least one adaptive filter in conformity with the error microphone signal and the reference microphone signal by computing coefficients that determine the response of the adaptive filter to minimize the ambient audio sounds at the error microphone, and wherein the processing circuit detects that an ambient audio event is occurring that could cause the adaptive filter to generate an undesirable component in the anti-noise signal and changes the adapting of the at least one adaptive filter independent of the computing of the coefficients by the coefficient control block, wherein the ambient audio event is wind noise, scratching on the housing of the personal audio device, a substantially tonal ambient sound, or a signal level of the reference microphone signal falling outside of a predetermined range. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of canceling ambient audio sounds in the proximity of a transducer of a personal audio device, the method comprising:
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first measuring ambient audio sounds with a reference microphone to produce a reference microphone signal; second measuring an output of the transducer and the ambient audio sounds at the transducer with an error microphone; adaptively generating an anti-noise signal by computing coefficients that control a response of an adaptive filter from a result of the first measuring and the second measuring for countering the effects of ambient audio sounds at an acoustic output of the transducer by adapting the response of the adaptive filter, wherein the adaptive filter filters an output of the reference microphone to generate the anti-noise signal; combining the anti-noise signal with a source audio signal to generate an audio signal provided to the transducer; detecting that an ambient audio event is occurring that could cause the adaptive filter to generate an undesirable component in the anti-noise signal, wherein the ambient audio event is wind noise, scratching on a housing of the personal audio device, a substantially tonal ambient sound, or a signal level of the reference microphone signal falling outside of a predetermined range; and responsive to the detecting, changing the adapting of the at least one adaptive filter independent of the computing of the coefficients. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An integrated circuit for implementing at least a portion of a personal audio device, comprising:
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an output for providing a signal to a transducer including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; a reference microphone input for receiving a reference microphone signal indicative of the ambient audio sounds; an error microphone input for receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements at least one adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit implements a coefficient control block that shapes the response of the at least one adaptive filter in conformity with the error microphone signal and the reference microphone signal by computing coefficients that determine the response of the adaptive filter to minimize the ambient audio sounds at the error microphone, and wherein the processing circuit detects that an ambient audio event is occurring that could cause the adaptive filter to generate an undesirable component in the anti-noise signal and changes the adapting of the at least one adaptive filter independent of the computing of the coefficients by the coefficient control block, wherein the ambient audio event is wind noise, scratching on a housing of the personal audio device, a substantially tonal ambient sound, or a signal level of the reference microphone signal falling outside of a predetermined range. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification